How to get the fully qualified host name + port number in Application_Start from Global.aspx?

Question

I tried

Uri uri = HttpContext.Current.Request.Url; String host = uri.Scheme + Uri.SchemeDelimiter + uri.Host + ":" + uri.Port; 

and it worked well on my local machine, but there is an exception when posting to IIS7 saying

 System.Web.HttpException: Request is not available in this context 

Does anyone know how to achieve this?

Answer 1

When the web application starts, the HTTP request is not processed.

You may need to process the Application_BeginRequest (Object Sender, EventArgs e) method in which the request context is available.

Edit: Here is a sample code inspired by the Mike Volodarsky block that Michael Shimmins linked to:

  void Application_BeginRequest(Object source, EventArgs e) { HttpApplication app = (HttpApplication)source; var host = FirstRequestInitialisation.Initialise(app.Context); } static class FirstRequestInitialisation { private static string host = null; private static Object s_lock = new Object(); // Initialise only on the first request public static string Initialise(HttpContext context) { if (string.IsNullOrEmpty(host)) { lock (s_lock) { if (string.IsNullOrEmpty(host)) { var uri = context.Request.Url; host = uri.GetLeftPart(UriPartial.Authority); } } } return host; } } 

Answer 2

The accepted answer is good, but in most cases (if the first request is an HTTP request), it is better to use the Session_Start event, which is raised once for each user every 20 minutes or so (not sure how long the session is valid). Application_BeginRequest will be run on every request.

 public void Session_Start(Object source, EventArgs e) { //Request / Request.Url is available here :) } 

Answer 3

Just answer it so that someone decides to really search in this thread ...

This works when starting the application in any mode ...

 typeof(HttpContext).GetField("_request", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(HttpContext.Current)